Arginine kinase: Differentiation of gene expression and protein activity in the red imported fire ant, Solenopsis invicta

Arginine kinase (AK), a primary enzyme in cell metabolism and adenosine 5′-triphosphate (ATP)-consuming processes, plays an important role in cellular energy metabolism and maintaining constant ATP levels in invertebrate cells. In order to identify genes that are differentially expressed between larvae and adults, queens and workers, and female alates (winged) and queens (wingless), AK cDNA was obtained from the red imported fire ant. The cDNA sequence of the gene has open reading frames of 1065 nucleotides, encoding a protein of 355 amino acid residues that includes the substrate recognition region, the signature sequence pattern of ATP:guanidino kinases, and an “actinin-type” actin binding domain. Northern blot analysis and protein activity analysis demonstrated that the expression of the AK gene and its protein activity were developmentally, caste specifically, and tissue specifically regulated in red imported fire ants with a descending order of worker> alate (winged adult) female> alate (winged adult) male> larvae> worker pupae ≈ alate pupae. These results suggest a different demand for energy-consumption and production in the different castes of the red imported fire ant, which may be linked to their different missions and physiological activities in the colonies. The highest level of the AK gene expression and activity was identified in head tissue of both female alates and workers and thorax tissue of workers, followed by thorax tissue of female alates and abdomen tissue of male alates, suggesting the main tissues or cells in these body parts, such as brain, neurons and muscles, which have been identified as the major tissues and/or cells that display high and variable rates of energy turnover in other organisms, play a key role in energy production and its utilization in the fire ant. In contrast, in the male alate, the highest AK expression and activity were found in the abdomen, suggesting that here energy demand may relate to sperm formation and reproduction.     

A new cavefish species, Sinocyclocheilus brevibarbatus (Teleostei: Cypriniformes: Cyprinidae), from Guangxi, China

A new species of the cavefish genus Sinocyclocheilus is described based on six specimens collected from a subterranean river in Du’an County in the Guangxi Zhuang Autonomous Region of southern China. Sinocyclocheilus brevibarbatus sp. nov. can be distinguished from all congeners by the following combination of characteristics: a completely scaled body with well-developed eyes and a strongly-humped back; an almost straight lateral line possessing 49–51 perforated scales; seven soft rays on the dorsal fin; a relatively large eyeball (3.3–5.7% of SL) and short maxillary and rictal barbels (1.7–5.7% and 4.5–7.0% of SL, respectively).     

Lanthanum suppresses osteoblastic differentiation via pertussis toxin‐sensitive G protein signaling in rat vascular smooth muscle cells

A major cellular event in vascular calcification is the phenotypic transformation of vascular smooth muscle cells (VSMCs) into osteoblast‐like cells. After demonstrating that lanthanum chloride (LaCl₃) suppresses hydrogen peroxide‐enhanced calcification in rat calcifying vascular cells (CVCs), here we report its effect on the osteoblastic differentiation of rat VSMCs, a process leading to the formation of CVCs. Cells were isolated from aortic media of male SD rats, and passages between three and eight were cultured in Dulbeccol's Modified Eagle's Medium (DMEM) containing 10% fetal bovine serum (FBS) and 10 mM β‐glycerophosphate (β‐GP) in the presence or absence of LaCl₃. Exposure of cells to LaCl₃ suppressed the β‐GP‐induced elevations in calcium deposition, alkaline phosphatase (ALP) activity, and Cbfa1/Runx2 expression, as well as the concomitant loss of SM α‐actin. Furthermore, LaCl₃ activated the phosphorylation of extracellular signal‐regulated kinase (ERK) and c‐Jun N‐terminal kinase (JNK), and the blockage of either pathway with a specific inhibitor abolished the effects of LaCl₃. In addition, pretreatment of the cells with pertussis toxin (PTx), an inhibitor of G protein‐mediated signaling pathway, repealed all the changes induced by LaCl₃. These findings demonstrate that LaCl₃ suppresses the β‐GP‐induced osteoblastic differentiation and calcification in rat VSMCs, and its effect is mediated by the activation of both ERK and JNK MAPK pathways via PTx‐sensitive G proteins. J. Cell. Biochem. 108: 1184–1191, 2009. © 2009 Wiley‐Liss, Inc.     

Enantioselective recognitions of chiral molecular tweezers containing imidazoliums for amino acids

Two kinds of novel chiral molecular tweezers containing imidazoliums were synthesized from L-alanine, L-phenylalanine, and L-glutamic acid. They are constructed by the chiral imidazolium pincers and two different spacers which are 1,3-bis (bromomethyl)benzene and 2,6-bis(bromomethyl)pyridine, respectively. The enantioselective recognition of L- and D-amino acid derivatives by these molecular tweezers was investigated by UV spectroscopic titration experiments and good enantioselectivities were obtained, which are highly sensitive to whether the spacer has the binding site and the pincers has the other aromatic rings besides imidazolium ring. The host molecular 3b.2PF6- showed remarkable enantioselectivity for N-Boc protected histidine methyl ester, affording K(L)/K(D) of 5.10.     

A micro-potentiometric hemoglobin immunosensor based on electropolymerized polypyrrole–gold nanoparticles composite

We report a novel micro-potentiometric hemoglobin (Hb) immunosensor based on electrochemically synthesized polypyrrole (PPy)–gold nanoparticles (AuNPs) composite. PPy–AuNPs film with AuNPs uniformly distributed in it was deposited on gold electrode surface by a simple and direct procedure, without the addition of any nanoparticles or reducing agent. And this generic method makes it possible to deposite different polymers on miniaturized electrodes. With the existence of AuNPs, the antibody immobilization onto the electrode surface was facilitated. Morphology study by field emission scanning electron microscope (FE-SEM) confirms the presence of AuNPs in PPy. Based on an ion-sensitive field-effect transistors (ISFETs) integrated chip, a micro-potentiometric immunosensor for Hb and hemoglobin-A1c (HbA1c) has been constructed. The sensor response was linear over the concentration range 60–180 μg/ml Hb and 4–18 μg/ml HbA1c. The Hb concentration in whole blood samples has also been analysed, with a linear dose–response behavior between 125 and 197 μg/ml and a sensitivity of 0.20 mV μg⁻¹ ml. The measuring ranges of the developed Hb and HbA1c immunosensors meet the clinical demand for measuring the HbA1c/Hb ratio of 5–20%. This sensor results in simple and rapid differential measurement of Hb and HbA1c, and has great potential to become an inexpensive and portable device for monitoring of diabetes.     

Synthesis of N-4-butylamine acridone and its use as fluorescent probe for ctDNA

A novel N-4-butylamine acridone (BAA), which is an acridone derivative was synthesized and characterized by IR, MS and (1)H NMR. The fluorescent characteristics of BAA was investigated in detail and used as the fluorescent probe for detection of calf thymus DNA (ctDNA). It was found that DNA was able to quench the fluorescence of BAA at 426 nm with the excitation at 254 nm. Under optimal conditions, the corresponding linear response range was from 1.0 to 20.0mg/L and the limit of detections (LOD) was 0.020 mg/L (defined as S/N=3). Moreover, the interaction between BAA and ctDNA was investigated by fluorescence, absorption and viscosity measurements. The results suggested that the interaction between BAA and ctDNA is groove binding in nature.     

Discovery of diarylpyridine derivatives as novel non-nucleoside HIV-1 reverse transcriptase inhibitors

Two series (4 and 5) of diarylpyridine derivatives were designed, synthesized, and evaluated for anti-HIV-1 activity. The most promising compound, 5e, inhibited HIV-1 IIIB, NL4-3, and RTMDR1 with low nanomolar EC₅₀ values and selectivity indexes of >10,000. The results of this study indicate that diarylpyridine can be used as a novel scaffold to derive a new class of potent NNRTIs, active against both wild-type and drug-resistant HIV-1 strains.     

Elucidation of the stability and functional regions of the human coronavirus OC43 nucleocapsid protein

Human coronavirus OC43 (HCoV‐OC43) is one of the causes of the “common cold” in human during seasons of cold weather. The primary function of the HCoV‐OC43 nucleocapsid protein (N protein) is to recognize viral genomic RNA, which leads to ribonucleocapsid formation. Here, we characterized the stability and identified the functional regions of the recombinant HCoV‐OC43 N protein. Circular dichroism and fluorescence measurements revealed that the HCoV‐OC43 N protein is more highly ordered and stabler than the SARS‐CoV N protein previously studied. Surface plasmon resonance (SPR) experiments showed that the affinity of HCoV‐OC43 N protein for RNA was approximately fivefold higher than that of N protein for DNA. Moreover, we found that the HCoV‐OC43 N protein contains three RNA‐binding regions in its N‐terminal region (residues 1–173) and central‐linker region (residues 174–232 and 233–300). The binding affinities of the truncated N proteins and RNA follow the order: residues 1–173–residues 233–300 > residues 174–232. SPR experiments demonstrated that the C‐terminal region (residues 301–448) of HCoV‐OC43 N protein lacks RNA‐binding activity, while crosslinking and gel filtration analyses revealed that the C‐terminal region is mainly involved in the oligomerization of the HCoV‐OC43 N protein. This study may benefit the understanding of the mechanism of HCoV‐OC43 nucleocapsid formation.